Injector for furnishing liquid at a low pressure to a vessel at a higher pressure

ABSTRACT

An injector for furnishing liquid at a low pressure to a vessel at a higher pressure comprising: an enclosed chamber having, at the bottom end, a centrally located downwardly converging combining tube, and in the middle, an annular trough whose circumferential lip defines a central opening connecting the upper end of the chamber to the lower end, means for conducting low pressure liquid into the trough from which it overflows, a nozzle centrally supported in the chamber having a downwardly and outwardly directed tube extending through the central opening and terminating in the lower chamber in an outwardly directed circumferential flange positioned below the lip of the trough for catching the liquid overflowing from the trough and causing it to pour over the flange in a continuous, circumferential concavely shaped curtain of liquid so that high pressure vapor furnished to the nozzle expands therein into the interior of the curtain of liquid condensing thereon to form a converging stream of liquid that enters the combining tube in a manner that maintains the velocity of the stream, and a diverging diffuser tube connected to the outlet of the combining tube for slowing the stream and converting its velocity head to a pressure head.

United States Patent [191 Bronicki [451 Aug. 20, 1974 INJECTOR FOR FURNISHING LIQUID AT A LOW PRESSURE TO A VESSEL AT A HIGHER PRESSURE [75] Inventor: Lucien Yehuda Bronicki, Rehovoth,

Israel [73] Assignee: Ormat Turbines (1965) Ltd.,

Yavne, Israel [22] Filed: Aug. 23, 1973 [21] Appl. No.: 390,982

[52] US. Cl. 60/667, 417/151, 60/656, 60/657 [51] Int. Cl. ..l F0lk 13/02, F0lc 17/00 [58] Field of Search 60/107; 417/183, 151

[56] References Cited UNITED STATES PATENTS 2,631,774 3/1953 Plummer, Jr. 417/151 3,314,236 4/1967 Zanoni 60/107 X 3,336,013 8/1967 Salo 60/107 X 3,686,867 8/1972 Hull 1 60/107 X 3,719,524 3/1973 Ripley et al 417/183 X Primary ExaminerEdgar W. Geoghegan Assistant Examiner-H. Burks, Sr. Attorney, Agent, or Firm-Ladas, Parry, Von Gehr, Goldsmith & Deschamps CONDENSER [5 7 ABSTRACT An injector for furnishing liquid at a low pressure to a vessel at a higher pressure comprising: an enclosed chamber having, at the bottom end, a centrally located downwardly converging combining tube, and in the middle, an annular trough whose circumferential lip defines a central opening connecting the upper end of the chamber to the lower end, means for conducting low pressure liquid into the trough from which it overflows, a nozzle centrally supported in the chamber having a downwardly and outwardly directed tube extending through the central opening and terminating in the lower chamber in an outwardly directed circumferential flange positioned below the lip of the trough for catching the liquid overflowing from the trough and causing it to pour over the flange in a continuous, circumferential concavely shaped curtain of liquid so that high pressure vapor furnished to the nozzle expands therein into the interior of the curtain of liquid condensing thereon to form a converging stream of liquid that enters the combining tube in a manner that maintains the velocity of the stream, and a diverging diffuser tube connected to the outlet of the combining tube for slowing the stream and converting its velocity head to a pressure head.

5 Claims, 1 Drawing Figure CONDENSATE PATENTEDwczo 1914 N 3, 830.064

VAPOUR SIDE CONDENSER TURBINE 49 CONDENSATE 2 BURNER FUEL M13 INJECTOR FOR FURNISHING LIQUID AT A LOW PRESSURE TO A VESSEL AT A HIGHER PRESSURE This invention relates to an injector for furnishing liquid at a lower pressure to a vessel at a higher pressure.

A pre-packaged power generating system operating on a closed Rankine cycle and suitable for use in remote, unmanned installation such as communication relay stations which are refuelled and serviced only infrequently, must be self-starting and as efficient and reliable as possible. Such a system is disclosed in US. Pat. No. 3,339,515; and the present invention is concerned with the feed pump by which condensate at the relatively low condensor pressure is fed back into the boiler which operates at a much higher pressure.

An injector pump is ideally s'uitable'for the system disclosed above because it is extremely simple in construction and operation and it has a high thermal efficiency. The problem with a pump of this type isits operating characteristic which is not compatible with the system requirements.

An injector is essentially a nozzle opening into a converging tube connected to the liquid to be pumped into the boiler. A small percentage of the boiler vapor is diverted to the nozzle where it expands therein to a high velocity and condenses into liquid in the combining tube imparting movement to the liquid whose velocity is maintained by the converging nature of the combining tube.

The velocity head so created is converted to a pressure head in a gradually diverging delivery tube or diffuser from which the liquid emerges at low speed but at a pressure sufficient to permit it to enter the boiler. An injector of this type is not suitable for returning liquid condensate to the boiler in a system of the type described above because such an injector has a very narrow working range: it is either fully on or fully off. This is not an ideal mode of operation in a system of the type described where, as a consequence of changesin the electrical load on the turbine driven by the vapour produced by the boiler, the mass flow of working fluid varies requiring a feed pump that can operate over a wide range. Even with this capability, a conventional feed pump would require operating controls to functionally relate its output to fluctuations in the load. The requirement for operating controls introduces a limitation on the reliability of the system as a whole which is highly undesirable in unmanned remotely located equipment to which there is limited access. Generally, any mechanism that adversely affects reliability is not to be desired in such equipment; and as a consequence it has not been possible, heretofore, to reduce the package size of a system of the type described without adversely affecting either the fuel consumption or the system reliability.

It is therefore an object of the present invention to provide a new and improved injector wherein the above described deficiencies and disadvantages are substantially reduced or overcome.

According to the present invention, there is provided an injector for furnishing liquidat a low pressure to a vessel at a higher pressure comprising: an enclosed chamber having at the bottom end, a centrally located downwardly converging combining tube, and in the middle, an annular trough whose circumfer- LII ential lip defines a central opening connecting the upper end of the chamber to the lower end, means for conducting low pressure liquid into the trough from which it overflows, a nozzle centrally supported in the chamber having a downwardly and outwardly directed tube extending through the central aperture and terminating in the lower chamber in an outwardly directed circumferential flange positioned below the lip of the trough for catching the liquid overflowing from the trough and causing such liquid to pour over the flange in a continuous, circumferential, concavely shaped curtain so that high pressure vapour furnished to the nozzle expands therein into the interior of the curtain of liquid condensing thereon to form a converging'stream of liquid that enters the combining tube in a manner that maintains the velocity of the stream, and a diverging delivery or diffuser tube connected to the outlet of the combining tube for slowing the liquid stream and converting its velocity head to a pressure head.

In the preferred embodiment the injector is used in a closed system operating on the Rankine cycle using an organic working fluid for furnishing liquid condensate at condenser pressure to a boiler at a higher pressure. In such case, the upper end of the chamber is adapted to be connected to the vapor side of the condenser and the diffuser tube is adapted to be connected to the boiler, the high pressure vapor expanded in the nozzle being a fixed percentage of the output'of the boiler, and the liquid conducted to the trough of the chamber being condensate from the condenser at the condenser pressure.

With this arrangement, the cone angle of the curtain I of liquid pouring over the flange on the nozzle will change inversely with the throughput of the system. At less than full load, the mass flow of working fluid will be relatively low and the cone angle of the curtain will be relatively large; while when the system operates at its rated load, the mass flow will be relatively large and the cone angle, accordingly, will be smaller. In each case, the percentage of vapour which is applied to the nozzle is the same so that the expanding vapor encounters the curtain of liquid with substantially little shock, condenses thereon, and remains self-contained within the curtain. The operation of the injector according to the present invention is thus self-regulating, eliminating the need for auxiliary controls; and the pumping action is effectively carried out throughout the entire practical range of operation of the system.

An embodiment of the invention is illustrated by way of example in the single FIGURE of the accompanying drawing which shows, in block diagram form, a closed system operating on the Rankine cycle in which the injector of the present invention has been incorporated.

Reference numeral 10 in the drawing designates a pre-packaged power plant operating on the Rankine cycle using an organic working fluid. Such fluid is heated in the boiler 11 by means of a burner 12 that is furnished with fuel from a tank 13. Conventionally, such fuel is liquefied gas that is maintained under high pressure in the fuel tank.

The working fluid is converted to a vapor at a relatively high pressure in the boiler and most of it, about 99%, flows into a turbine 14 where it expands and does useful work in turning a generator that constitutes the load 15 on the turbine. The turbine exhausts into a closed heat exchanger 16 where condensation occurs producing a liquid condensate that is fed back into the boiler by injector pump 17 made in accordance with the present invention. The purpose of the injector is to pressurize the liquid condensate, which is at the turbine back pressure, so that the liquid condensate can enter the boiler which is at a relatively higher pressure than the liquid condensate extracted from the condenser.

Injector l7 achieves this result over a wide range of mass flow rates of the working fluid and without the need for any auxiliary controls to functionally relate its operating characteristics to the load imposed on the turbine. The injector 17 comprises a tank 18 forming an enclosed chamber with central openings 18a and 18b in the top and bottom respectively, an annular trough l9 internally mounted in the tank, a special nozzle 20 centrally located in the tank, a combining tube 21 attached to the bottom of the tank in alignment with the opening 18b therein, and a delivery or diffuser tube 22 connected to the combining tube 21. A suitable duct 23 aligned with and connected to the opening 18a and the top of the tank connects the top chamber 24 of the tank to the condenser and turbine exhaust thereby maintaining the pressure in the top chamber at the back pressure of the system. The trough 19 is annular in shape and of the same outer diameter as the inner diameter of the tank, being attached-thereto at the middle of the tank dividing it into upper chamber 24 and lower chamber 25. The circumferential lip 26 on the trough defines a central opening 27 that interconnects the upper and other chambers.

Terminating in the tank is a conduit 28 that is connected to the sump of the condenser 16 for the purpose of conducting the low pressure liquid condensate from the sump into the trough 19 from which the liquid flows over the lip 26 and into the lower chamber 25.

Centrally supported in the tank is the nozzle 20 which comprises a header 30 that receives vapor from boiler 11 through a suitable conduit 29, and a downwardly facing expansion tube 31 that extends through the central opening 27 and terminates in the lower chamber in an outwardly directed circumferential flange 32 positioned below the lip 26 of the trough. Flange 32, which catches the liquid condensate overflowing the trough, has a rounded contour that fairs smoothly into the inner surface of tube 31 within which vapor from the header expands. The upwardly curved free edge of the flange 32 forms an annular cuplike depression that serves to collect the overflow from trough l9 and acts as a temporary reservoir from which liquid condensate may pour smoothly over the flange in a continuous, circumferentially extending concavely shaped curtain 33 of liquid that forms an annular sheath entirely containing the expanding vapors exhausting from tube 31. Such vapors encounter the curtain 33 with substantially little shock and condense thereon to form a converging stream of liquid that enters combining tube 21. The latter converges in order to maintain the velocity of the stream which is given impetus by interacting with the expanding gases. Below the delivery tube and connected thereto is a diverging delivery or diffuser tube 22 which permits the stream to slow converting its velocity head to a pressure head sufficient to permit the liquid to pass through a check valve 50 and enter the boiler for re-circulation.

The cone angle of the curtain of liquid pouring over the flange 32 is designated by the letter a in the drawing; and this angle changes automatically in an inverse relationship with the mass flow of the working fluid. At light loads, the mass flow will be relatively small and the cone angle will be relatively large as suggested by the broken lines in the drawing. When the load increases, the mass flow increases causing the cone angle to decrease with an accompanying increase in the annular cross-section of the curtain. The stream thus intercepts the gradually sloping walls of the combining tube 21 at a lower position than previously. This arrangement provides the self-regulating compensation so essential to reliable operation of a device of the type described in a remote location.

In the preferred embodiment, the conduit 28 by which the upper chamber of the tank is maintained at the back pressure of the system, contains the conduit 23 by which liquid condensate is conducted to the tank. Specifically the conduit 28 is centrally located in the larger conduit for as great a distance as possible in order to prevent freezing of liquid condensate under extremely cold ambient conditions.

It is further preferred that the relationship between the location of the pump 17 on the one hand and the boiler, condenser and turbine on the other be as follows:

l. the pump should be above the boiler so that liquid therein will drain into the boiler by gravity on shutdown; and

2. the condensate inlet to the pump should be below the bearings 49 of the turbine, and the bearings themselves should be below the condenser so that condensate flows by gravity from the condenser through the bearings and into the trough 19 of the pump. As a consequence of this arrangement, the system will be self-starting in that at shutdown, all of the liquid will be in the boiler and the bearings will be dry. With some organic working fluids, the ambient temperature to which the system is subjected is such that all of the liquid will be in a frozen state in the boiler. No frozen material will block the flow of vapor on start up or will be present in the bearings to prevent rotation of the turbine.

At start up, heat is applied to the boiler causing the latter to produce vapor which initially passes through the turbine without turning the same. As the initial vapor condenses, it runs down into the bearings and into the pump 17. Eventually, sufficient vapor is developed to begin to rotate the turbine and at such time, the bearings will be sufficiently lubricated. Furthermore, a curtain of liquid 33 will be present in the pump which 'will begin operation as the flow of working fluid increases.

While the invention has been disclosed as a part of a closed cycle system operating on the Rankine cycle and utilizing an organic working fluid, it should be understood that the invention has application to other systems and other working fluids. For example, the invention is applicable as a water pump, in which case steam would be expanded in the nozzle.

I claim: 1. An injector for furnishing liquid at a low pressure to a vessel at a higher pressure comprising:

a. an enclosed chamber having a bottom end; b. a downwardly converging combining tube centrally located in said bottom end; c. an annular trough inside the chamber having a circumferential lip defining a central opening connecting the upper end of the chamber to the lower end;

d. means for conducting low pressure liquid into the trough;

e. a nozzle centrally supported in the chamber having a downwardly and outwardly directed tube extending through the central opening and terminating in the lower end of the chamber in an outwardly directed circumferential flange positioned below the lip of the trough for catching liquid overflowing from the trough and causing it to pour over the flange in a continuous, circumferential concavely shaped curtain of liquid so that high pressure vapour furnished to the nozzle expands therein into the interior of the curtain of liquid condensing thereon to form a converging stream of liquid that enters the combining tube in a manner that maintains the velocity of the stream; and

f. a diverging diffuser tube connected to the outlet of the combining tube for slowing the stream and converting its velocity head to a pressure head.

2. An injector according to claim 1 used in a closed system operating on the Rankine cycle using an organic working fluid for furnishing liquid condensate at condenser pressure to a boiler at a higher pressure, the upper end of the chamber adapted to be connected to the vapour side of the condenser and the diffuser tube adapted to be connected to the boiler, the high pressure vapour expanded in the nozzle being a fixed percentage of the output of the boiler, and the liquid conducted to the trough being condensate from the condenser at the condenser pressure.

3. An injector according to claim 2 wherein the condensate conducted to the trough passes by conduit through a larger conduit connecting the upper end of the chamber to the vapour side of the condenser.

4. An injector according to claim 3 wherein the liquid condensate, before being applied to the injector, passes through the bearings of a turbine driven by the vapourized working fluid produced by the boiler.

5. An injector according to claim 4 wherein the injector and turbine are located above the level of liquid in the boiler so that the system is self-draining and can be started merely by applying heat to the boiler. 

1. An injector for furnishing liquid at a low pressure to a vessel at a higher pressure comprising: a. an enclosed chamber having a bottom end; b. a downwardly converging combining tube centrally located in said bottom end; c. an annular trough inside the chamber having a circumferential lip defining a central opening connecting the upper end of the chamber to the lower end; d. means for conducting low pressure liquid into the trough; e. a nozzle centrally supported in the chamber having a downwardly and outwardly directed tube extending through the central opening and terminating in the lower end of the chamber in an outwardly directed circumferential flange positioned below the lip of the trough for catching liquid overflowing from the trough and causing it to pour over the flange in a continuous, circumferential concavely shaped cuRtain of liquid so that high pressure vapour furnished to the nozzle expands therein into the interior of the curtain of liquid condensing thereon to form a converging stream of liquid that enters the combining tube in a manner that maintains the velocity of the stream; and f. a diverging diffuser tube connected to the outlet of the combining tube for slowing the stream and converting its velocity head to a pressure head.
 2. An injector according to claim 1 used in a closed system operating on the Rankine cycle using an organic working fluid for furnishing liquid condensate at condenser pressure to a boiler at a higher pressure, the upper end of the chamber adapted to be connected to the vapour side of the condenser and the diffuser tube adapted to be connected to the boiler, the high pressure vapour expanded in the nozzle being a fixed percentage of the output of the boiler, and the liquid conducted to the trough being condensate from the condenser at the condenser pressure.
 3. An injector according to claim 2 wherein the condensate conducted to the trough passes by conduit through a larger conduit connecting the upper end of the chamber to the vapour side of the condenser.
 4. An injector according to claim 3 wherein the liquid condensate, before being applied to the injector, passes through the bearings of a turbine driven by the vapourized working fluid produced by the boiler.
 5. An injector according to claim 4 wherein the injector and turbine are located above the level of liquid in the boiler so that the system is self-draining and can be started merely by applying heat to the boiler. 